Building, expanding, and upgrading radio communication systems, such as a 2nd generation system, e.g. a Global System for Mobile communications (GSM) system, or a 3rd Generation Partnership Project (3GPP) system, e.g. a Universal Mobile Telecommunications system (UMTS), involves enormous costs when good coverage should be achieved. In order to achieve sufficient coverage over the whole geographical area being covered by the radio communication system, a very large number of base stations have to be built, which is very expensive.
For example, a system operator normally has to provide sufficient coverage for more or less the whole geographical area of a country, in which the system operator provides its services in order to be commercially successful. Especially, in some geographical areas, in which there is relatively low activity in the radio communication system, offering adequate coverage by building a full Radio Access Network (RAN) completely covering that area is rarely profitable.
Thus, in a traditional radio communication system, each communication system operator has to make extensive investments in order to provide sufficient coverage for its customers. Also, when new technologies are rolled out, each system operator has to upgrade its RAN accordingly, which is also costly.
In order to solve these problems, system operators have started to share their RANs with each other. Basically, physical base stations and control nodes in the radio communication system are shared by a number of system operators.
The physical base stations are divided into a number of logical base stations, such that radio resources of such a physical base station are shared by a number of logical base stations. A logical base station is a virtual base station, which can function independently to perform essentially all radio communication functions a physical base station would normally be expected to perform.
Thus, the prior art RAN sharing approach is based on a logical separation of the RAN. The approach supports that Core Networks (CNs) of multiple system operators connect to a single control node in the radio communication system, such as a Base Station Controller (BSC), or a Radio Network Controller (RNC).
More in detail, the prior art RAN sharing solution is based on a logical separation of RAN, which is achieved by assigning specific carriers to individual operators. A Public Land Mobile Network (PLMN) id, which belongs to a specific system operator, is broadcast in the radio carrier or radio carriers being assigned to that specific system operator. Also, the CNs of the multiple system operators can connect to a single control node in the radio communication system, such as a BSC or a RNC, via e.g. Iu flex protocol for 3GPP.
Also, an Element Management System (EMS) is shared by a number of system operators and is managed by a primary system operator. The primary system operator is one of the system operators sharing the RAN. Usually, the primary system operator is the system operator being the owner of the physical nodes of the RAN being shared by the system operators. The other system operators sharing a physical base station are denoted secondary system operators.
The shared EMS facilitates connections to Network Management Systems (NMS) of individual operators. An individual system operator can provide certain Configuration Management (CM) instructions to the shared EMS through their own NMS. The system operator can provide instructions regarding some cell level related parameters, i.e. regarding parameters relating to specific sectors and/or carriers of a base station. However, some of the site level related parameters, i.e. parameters relating to the whole base station, such as Quality of Service (QoS) related parameters, can not be set by individual system operators not being the primary system operator. Also, the shared EMS is managed by the primary system operator.
The prior art sharing solution offers cost advantages due to sharing of expensive hardware and software equipment. However, the prior art solution also has drawbacks regarding control over and flexibility of the shared RAN. In the prior art sharing solutions, a system operator not being a primary operator has a very restricted control over the shared RAN, which is experienced as a problem by the system operators.